Lightning-arrester.



F. B. COREY.

LIGHTNING ARRESTER.

APPucATmN man 1AN.23. 1915.

Patented Nov. 23, 1915.

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Inuenzar, 7 /a Winesses, /i MGi/ZM F. B. COREY.

LIGHTNiNG ARHESTER.

APPLICATION FILED 1AN.23. 1915 Patented Nov. 23, 1915.

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In venor, Za/@ Wz'znesses,

FRED B. COREY, OF EDGEWOOD, PENNSYLVANIA.

LIGHTNING-BREWER Specification of Letters Patent.

Patented Nov. 23, 1915.

Application led January 23, 1915. Serial No. 3,962.

T 0 all whom t may concern.'

Be it known that I, Fano B. COREY, a citizen of the United States, residing at Edgewood. in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Lightning-Arresters, of which the following is a. specification.

My invention relates to lightning arresters and especially to that class of lightning arresters in which sprak-gaps are provided,v between the circuit to be protected and the ground to which thel static charge is to be diverted.

The obiect of my invention is to provide such a lightning arrester that will give ample protection to the apparatus connected with it and that will not itself be damaged by the passage to ground of a heavy induced discharge through it.

My invention consists in the combination with multiple vspark-gaps in a lightning arrester. ora group of lightning arresters connectedl to the same circuit, of coils, consisting of a. few turns of wire, in series with the said spark-gaps and arranged in pairs. each pair being in mutually inductive relation and differentially connected so as to oier a non-inductive path to the discharge only when this discharge is equally divided between the said multiple spark-gaps, thus tending automatically to equalize the discharge through all of the spark-gaps and preventserious burning at any one of them.

In the drawings that illustrate my invention, Figure 1 is a top view of a lightning arrester having two spark-gaps and embodying mv improvements. Fig. 2 is a side view, partiallv in section, and Fig. 3 is a transverse section through the center of the same arrester. Fig. 4 is a diagram showing the arrangement of the differentially arranged coils when4 the number of sparkgaps is greater than two.

Referring to Figs. 1 2 and 3, A represents a hollow block of porcelain or other insulating material on and in which the other parts are mounted. B is a terminal screw with a. thin square head, held i'n place in the base A by the nut N1. On this terminal screw is mounted the disk C. preferablymade of some non-fusible, conducting material such as carbon. This disk is held in place by the nut N6 and above this nut are two washers 'VV-1 and 72 and the terminal nuts T1 and T2. 0n either side of the terminal screw B are similarly mounted screws` D1 and D2 held in place by the nuts N2 and N3 respectively and carrying the disks E1 and E2 which are preferably made of brass or other metal and have their outer cylindri cal surfaces knurled to form a large number of points rather than a smooth surface. These disks are held in place by the nuts N7, N8, N and N1". On either side of these screws D1 and D2, are mounted the terminal screws F1 and F2 which are held in place by the nuts N4 and N5 yabove which are the washersVVS. VW. 75 and IVG and the terminal nuts T3, T, T5 and T". These screws F1 and F2 are joined by the copper wire K, making them electrically as one, the two screws being provided merely for convenience in connecting the arrester into the circuit to be protected. Inclosed within the base A is an insulating tube P, upon which two pieces of wire H and J, preferably of copper, are wound, forming two concentric helices. The helical conduct-or H serves to connect the screw D1 to the conductor K and the termin-als F1 and F2 attached thereto. In like manner the helical conductor J serves to connect the screw D2 to the conductor K and terminals F1 and F2. After the parts are mounted in place, the interior space S is filled with melted sealing wax o-r other insulating compound of an adhesive nature and the cover plate L is inserted and is held in place by the solidified sealing compound. 1

`The operation of this lightnin arrester is as follows: The terminal post is connected to ground. The static charge, entering the arrester through one of the terminal screws F1 or F2, will vflow to the metal disks E1 and E2 and will jump to ground through the disk C and the terminal screw B. The charge will tend to jump the shorter of the two spark-gaps G1 or G2. The discharge across the spark-gap is alternating in character and of high frequency. The helical conductor H or J therefore introduces a reactance in seriesV with the spark-gap. When, however, the discharge passes equally across the two spark-gaps in multiple, the helical conductors H and J become non-inductive, as the fiuX that would be set up within one helix is neutralized by the flow of electrical energy in the other helix. Since, therefore, the impedance'of the path of the discharge is least when it is equally divided across the two spark-gaps, it will automativcally so divide, as it will thus ind the path of least impedance to ground.

Referring now to Fig. 4, the connections are shown by which the discharge is equalside of each is connected to conductor Z through the differentially arranged coils X1, X2, X3, X4, X5, X6 and X2. The coil X1 is formed by conductors'a1 and b1 united at c1. The remaining coils are similarly formed of conductors similarly designated. The amount of discharge passing across the spark-gaps V1 and V2 and through the conductors a1 and b1 is equalized by the coil X1 and the amount passing through the remaining pairs of spark-gaps V3 and V4, V5 and V6 and V7 and Va are equalized in the same way by the coils X2, X3 and X4. In like manner the discharge passing through coil X1v and conductor as and that passing through coil X2 and conductor b5 is equalized by the coil X5, and that passing through conductors af and b is equalized by the coil X". Thus, also, by the action of the coil X7, the discharge through the conductor a7 is equalized with that through conductor b2. Thus, by the combined action of seven differentially arranged coils the discharge across the eight spark-gaps is equalized so that one-eighth of the discharge passes each spark-gap. It will be seen that in accordance with my invention, two spark-gaps may be equalized Withv one coil, four spark-gaps with three coils, eight spark-gaps With seven coils or sixteen spark-gaps with fifteen coils.

I do not desire to limit myself to the eX act construction and arrangement of parts here shown, but aim in the appended claims to cover all modifications which are within the scope of my invention.

What I claim as new and desire'to secure by Letters Patent of the United States is- 1. In a lightning arrester, the combination of multiple spark-gaps and reactance coils in series with the said spark-gaps, said coils comprising each a pair of concentric windings reversely wound whereby their reactance is neutralized when the current flowing in each of the said windings is equal.

. 2. In a lightning arrester, the combination of multiple spark-gaps and reactance coils in series With the said spark-gaps, said coils comprising each a pair of coils reversely Wound on a single core whereby their reactance is neutralized when the current flowing in each of the coils is equal.

8. In a lightning arrester, the combination of two multiple spark-gaps and a coil comprisingv a pair of concentric windings each in series with one of the said spark-gaps, the said windings being reversely wound whereby their reactance is neutralized when the current owing in` each of the windings is equal.

4. In a lightning arrester, an insulating base, two spark-gaps mounted thereon, one

electrode of each ot the said spark-gaps be` ing connected to one terminal of the said lightning arrester, the opposite electrodes ot' the said spark-gaps being connected to the other terminal of the lightning arrester through concentric reactance coils reversely wound whereby their reactance is neutralized when the current flowing in each of the said coils is equal.

In Witness whereof, I have hereunto Set my hand this 22 day of January, 1915.

FRED B. COREY.

Witnesses:

-DoRTHnA ATWELL, Jos. A. BROOKS. 

